Subject: Re: [linux-audio-dev] terrible latencytest results.. why??
From: Maarten de Boer (maarten.deboer_AT_iua.upf.es)
Date: Fri Nov 09 2001 - 10:35:08 EET
Roger Larsson <roger.larsson_AT_norran.net> wrote:
> They are not bad either... (sub 10 ms)
I think it is bad. I want the <3 ms :-)
I will be added latency in the processing (fft, ifft)
and it all adds up.
> > Something is definitely very wrong here. I am running kernel
> > 2.4.13 patched with preempt-kernel-rml-2.4.13-2.patch
> And you have enabled it in .config? (checking the obvious...)
Yeah, I triple checked the obvious (also: did I run lilo, did
lilo use the right vmlinuz)
> But wait... an AMD....
> They have some 3DNow specific kernel optimizations that causes trouble -
> they need to disable preemtion (uses fp registers...)
Hmm.. Does anybody have more information about this? Could I disable these
optimizations compiling for another CPU (386, or maybe even Pentium Classic?)
I suppose the performance penalty that would give would be acceptable. Latency
is more important.
Would Andrew Morton's LL patches also be affected by this?
Maarten
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